Question 1: Define the Three Domain System and identify the three domains it includes.

Answer: The Three Domain System classifies all living organisms into three domains: Bacteria, Archaea, and Eukarya, based on genetic and structural differences.

Question 2: Explain one key difference between organisms in the Bacteria and Archaea domains.

Answer: Organisms in the Bacteria domain have cell walls made of peptidoglycan, whereas Archaea have unique cell wall compositions and can survive in more extreme environments.

Question 3: What is the primary basis for dividing organisms into the three domains?

Answer: Genetic differences in ribosomal RNA (rRNA) sequences are the primary basis for dividing organisms into the three domains.

Question 1: If two organisms from different domains share 85% similarity in their rRNA gene sequences, calculate the percentage difference in their sequences.

Answer: 15%

Question 2: A particular bacterial species has a genome size of 4.6 million base pairs. If a related archaeal species has a genome size of 3.2 million base pairs, calculate the percentage difference in genome sizes.

Answer: 30.43%

Question 3: Using the formula for genetic similarity: % similarity = (number of identical base pairs / total base pairs) × 100, if 3.9 million base pairs are identical between two genomes of 4.6 million and 3.2 million base pairs respectively, what is the percentage similarity?

Answer: Approximately 84.78%

Question 1: Describe a safe laboratory method for extracting DNA from bacterial cells to analyse their genetic material.

Answer: Use sterile techniques, wear protective gloves and goggles, work in a well-ventilated area, and dispose of biological waste properly.

Question 2: Identify two variables that should be controlled when comparing genetic material from organisms in different domains.

Answer: Temperature and pH levels during DNA extraction.

Question 3: Suggest a reason why understanding the differences between the three domains is important for developing antibiotics.

Answer: Because bacteria and archaea have different cell structures and genetic makeup, which affects how antibiotics target them without harming beneficial organisms.

Question 1: A scientist finds that a new microorganism's rRNA sequence shares 92% similarity with known Archaea. What can be inferred about its classification?

Answer: It is likely to belong to the Archaea domain, as high similarity suggests close genetic relation.

Question 2: If a bacterial genome shows 99% similarity to another bacterial species, but only 75% similarity to an archaeal genome, what does this suggest about their evolutionary relationship?

Answer: They are more closely related to each other and likely belong to the same domain (Bacteria), with less relation to Archaea.

Question 1: Discuss how the understanding of the Three Domain System can influence the development of probiotics or antibiotics.

Answer: Understanding the Three Domain System helps scientists identify which microorganisms are beneficial, pathogenic, or neutral. This knowledge guides the development of targeted probiotics to promote health and antibiotics that specifically target pathogenic bacteria without harming beneficial archaea or eukaryotic cells.

Question 2: Describe a scenario in biotechnology where classifying organisms into the three domains can aid in developing sustainable solutions.

Answer: In biotechnology, classifying microbes accurately allows for the engineering of extremophiles (archaea) to produce enzymes for industrial processes like biofuel production under extreme conditions, leading to more sustainable and efficient solutions.